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ATX power supply 550W with Hyper LCS-X family

Posted by: sdseries on

Dear Team,

Could you please help with PI Expert Suite as i am not able to select multiple outputs such as 5v,-5v,3.3v,-3.3v,12v,-12v for the same design ,it allows to choose only one as negative not all

also it gives me error/warning when i tried to input 5v with 20A as input is greater than maximum limit of 12 ,does it means that PI suit only supports 12A

Please suggest me best option with hyperLCS-X + other PI product combination for my ATX 550W project

Thanks in Advance

BR,
Saurabh

Comments

Submitted by PI-Cylon on 12/17/2020

Hi Saurabh,


https://ac-dc.power.com/applications/pc-power/ lists the PI products that are best suited for design of PC power supplies.


Your power level requirement of 550W exceeds the maximum of HiperLCS (440W). HiperPFS has the required power, but will need an extra DC-DC stage to give you the desired ouput. HiperTFS would also not be optimal for your application. These products are only supported in PI XLS and don't have PI Expert support.


Could you please clarify which product you are trying to use when getting a maximum limit of 12A? Also, for which product are you trying to select the multiple outputs?


I will more information about your design specifications before I can help you any further. For what input voltage are you designing? What exact outputs do you need? 12/-12/5/-5/3/-3.3V? What are the current requirements on these outputs? Are there efficiency requirements that you need to meet?

Submitted by sdseries on 12/17/2020

Dear PI Expert,

Thanks for giving me your valuable response

Please refer the details for the Product as below

Product : ATX Power Supply for Desktops ATX VERSION
ATX 12V v2.4

Design Specifications:

Operating minimum 80% efficiency at full load

Active Power Factor Correction (PFC)

AC Input: 90V – 265V (8.4Amps) 50-60 Hz

DC Outputs
O1 +3.3V 20 A
O2 +5V 20A
O3 +12V 45.8A
O4 -12V 0.3A
O5 +5V 3A

Thanks in Advance

BR,
Saurabh

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Submitted by PI-Cylon on 12/28/2020

Hi Saurabh,


first, let me address your earlier question about the 12A limit. This is a limitation of the Flyback topology in PI Expert. For Flyback designs with more than 12A on the output, the losses on the secondary would become too large to meet efficiency requirements. For 20A a different topology is recommended.


The HiperLCS is the most appropriate converter for your application, but it has a limitation of 440W output power and requires a high-voltage input. The high-voltage input can be provided by a HiperPFS-3 or HiperPFS-4 PFC stage.


On the HiperLCS page https://ac-dc.power.com/products/hiper-family/hiperlcs/ you can see a number of design examples (DERs) using the part. DER-385 https://ac-dc.power.com/design-support/reference-designs/design-examples/der-385-255-w-80-plus-platinum-pc-power/ shows an example of a high current 12V output with 91%+ system efficiency at 115VAC. To satisfy your 12V output you can make a similar design, but with a higher output current and utilizing HiperPFS-3/HiperPFS-4.


For Universal input (90-265 VAC, 50-60Hz), the HiperPFS-3 and HiperPFS-4 have a limitation of 405W continuous and 450W peak power output. Assuming a well-designed HiperLCS stage with 95% efficiency, you may be able to get 405W / 12V / 0.95 = 35.5A continuous and 450W / 12V / 0.95 = 39.5A peak current on your 12V output. This maximum practical power is computed assuming good thermal management for the parts.


The 3.3V 20A output and 5V 20A will need a separate HiperLCS and HiperPFS converters. The low-power -12V 0.3A and 5V 3A can be supplied by an InnoSwitch Converter.


In summary, I would recommend the following to most closely meet your requirements (2 HiperPFS-4 parts, 2 HiperLCS parts, 1 InnoSwitch3-CE part):


HiperPFS-4 PFC stage #1 -> HiperLCS LLC Converter with a 12V 35.5A (39.5A peak) output
HiperPFS-4 PFC stage #2 -> HiperLCS LLC Converter with 3.3V 20A and 5V 20A outputs
HiperPFS-4 PFC stage #2 -> InnoSwitch3-CE Flyback with 5V 3A and -12V 0.3A outputs


Well-designed HiperPFS and HiperLCS stages will have efficiency > 90% for all input conditions and should have no problem satisfying your 80% system efficiency.


Power Integration provides PI XLS spreadsheets to help design HiperPFS-4 and HiperLCS converters. InnoSwitch3-CE converters can be designed using either PI Expert or PI XLS.


Let me know if this answers your questions.

Submitted by sdseries on 01/04/2021

Dear PI Expert,

Highly appreciate your swift reply.

I have gone through from your valuable suggestion and recommendations regarding the Topology and PI devices use .
Now it is very clear from my understanding point view and answers all my questions

Just want to know about Power sequencing required as per design guidelines from ATX v2.52 latest version

Requirement as per V2.52 ATX document:

The +12V1 DC / +12V2 DC and +5 VDC output levels must be equal to or greater than the +3.3 VDC output at all times during power-up and normal operation. The time between any output of +12V1 DC / +12V2 DC and +5 VDC reaching its minimum in- regulation level and +3.3 VDC reaching its minimum in-regulation level must be ≤ 20 ms as shown in the below figure.

So for this requirement i have gone through various Supervisor IC's(Timing, Housekeeping and Control ) from various Suppliers but about the compatibility with PI devices and recommendations i am not sure

I would be more happy if you could enlighten your views on some Supervisor IC(Timing, Housekeeping and Control ) or PI Devices/ DER Examples for Power sequencing guidelines of ATX

Thanks for all your Support and I greatly appreciate all your replies

BR
Saurabh Dharne

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Submitted by PI-Cylon on 01/15/2021

Dear Saurabh,


Power Integrations does not focus on the design of ATX power supplies and has limited experience with power sequencing. We are also concerned that adding power sequencing circuitry on top of the proposed HiperLCS solution will result in a design that is complicated and not cost effective.